PLATYCUINID.E. PLATYCRINITES. 21 



The only portion of the proboscis which could possibly have been contractile is that 

 near its extreme point, where the plates are small and irregidar in shape ; but the power 

 of contraction must have been exceedingly limited, even if the animal jjossessed the 

 means of shortening the organ in the slightest degree whatever. 



Though the proboscis of this, as well as that of the preceding species, possessed a 

 sufficient degree of flexure to enable the animal to direct it on cither side towards the 

 points where the rays might have captured an object of nourishment, it is imagined that 

 -the tentacula passed it along in succession until it was securely deposited in the oral 

 aperture, which was turned to receive the expected supply of food. That the degree of 

 phancy possessed by the proboscis was inconsiderable when compared with the wonder- 

 ful degree of flexure in the rays, we consider evident, from the arrangement of the 

 proboscidial plates; and we are borne out in this opinion by the fact, that of the 

 numerous specimens of Platj/crinites which we have discovered, with the oral tube 

 beautifully developed, in no one instance have we found it much curved or contorted. 

 In another genus it was evidently different, for we have obtained the oral organ much 

 bent, and l}ing in a great variety of positions. 



Rays. — The main rays are five m number, each composed of a single cuneiform joint, 

 from which proceed the first bifui'cations, consisting of two joints each ; these are again 

 succeeded by the second bifurcations, makmg the total number of rays twenty. 



The same structiu-al modifications are observed in the rays of this species as m the 

 P. Icevis. 



The strongly formed basal joints with double excavations for the muscles, vvith their 

 transverse ridges and marginal strite, impart strength, with the required degree of 

 flexure to the secondary rays, which present a similar mode of articulation to the basal 

 joints. Between the upper cuneiform joints and the double scries, are several wedge- 

 shaped joints, similar to those described in the t}'23ical species. 



It wiU be obvious, by studjiug the arrangement of the ray joints, that those constitut- 

 ing the lower portions must have possessed less flexui-e than the upper parts, where the 

 double series admitted of a much greater degree of pliabihty. In this respect the rays 

 somewhat resembled a nicely adjusted elastic fishing rod, moderately rigid at its base, 

 but gradually becoming finer and more pliant towards the opposite extremity. 



The rays of this species are finer and proportionally shorter than in tlie P. hcris. 



Tentacula. — The dehcate frame work of the tentacida has in many instances been 

 so well preserved, that every joint is as clearly seen as if the animal was stiU alive. In 

 this species they are equally numerous along the rays, and are otherwise similar to those 

 of the tj^ical species. They are perhaps rather finer, which in some instances makes 

 them appear longer. 



